Gemstone



FIG. 1 is a perspective view of a gemstone in accordance with the present design;

FIG. 2 is a front view thereof, wherein the back view, left side view, and right side view are mirror images of the front view;

FIG. 3 is a top view thereof; and,

FIG. 4 is a bottom view thereof. 

CLAIM The ornamental design for a gemstone, as shown and described. 